Piston knurling device



Jan, 4, 1966 N. J. DAM 3,226,966

PISTON KNURLING DEVICE Filed Jan. 2, 1964 2 Sheets-Sheet 1 8 159 46 62 46 49 a 42 41 44 5 5 E wllwl 6 I u z 57 flmlh. 26 57 E 5 57a 12 uinn ,nilw'" MM '5? TN I 376 INVENTOR.

/V/ELS J. DAM

Jan, 4, 19%5 N. J. DAM 3,226,966

PISTON KNURLING DEVICE Filed Jan. 2, 1964 2 Sheets-Sheet 2 l NVENTOR.

41/54: (A DAM United States Patent Ciiice 3,226,966 Patented Jan. 4, 1966 3,226,966 PISTON KNURLING DEVICE Niels J. Dam, Tyler, Minna, assignor to Tyler Engineering and Manufacturing Co., Inc, Tyler, Minn, a corporation of Minnesota Filed Jan. 2, 1964, Ser. No. 335,053 10 Claims. (Cl. 72-215) This invention relates to a compact, portable piston knurling device for use in knurling the exterior surface of the skirt of conventional pistons employed in internal combustion engines.

An object of this invention is to provide a novel compact portable piston knurling device for use in knurling the exterior skirt surface of a piston, and having provision for mounting pistons of varying diameters and differently contoured inner skirt surfaces thereon, without necessitating removal of the connecting rod, and having a variously adjustable knurling wheel for producing knurled bands on the exterior surface between the wrist pin bosses of the piston skirt.

Another object of this invention is to provide a novel knurling device of the class described and including readily releasable clamping means insertable into the wrist pin of the piston assembly to positively and uniformly urge the piston downwardly upon the arcuate bearing surface of a support member whereby to minimize danger of damage to the piston during the knurling operation.

A further object of this invention is to provide a novel piston knurling device including an adjustable support for very nicely supporting thereon pistons of varying sizes and differently contoured inner skirt surfaces, and also having a readily adjustable knurling arm with a knurling wheel thereon, the knurling arm not only being adjustable for knurling piston skirts of varying diameters, but also being readily adjustable longitudinally of the piston so that a plurality of knurling bands may be readily and efficiently produced on the outer skirt surface of the piston.

These and other objects and advantages of the invention will more fully appear from the following description made in connection with the accompanying drawings, wherein like character references refer to the same or similar parts throughout the several views, and in which:

FIG. 1 is a side elevational view of my novel piston knurling device with parts thereof broken away for clarity;

FIG. 2 is a cross sectional view on an enlarged scale taken approximately along line 2-2 of FIG. 1 and looking in the direction of the arrows, certain parts thereof being broken away for clarity;

FIG. 3 is an enlarged fragmentary cross sectional view illustrating one end of the knurling arm and also illustrating details of the knurling wheel mechanism;

FIG. 4 is a cross sectional view on the same scale as FIG. 3 and taken approximately along line 44 of FIG. 3 and looking in the direction of the arrows;

FIG. 5 is a cross sectional view taken approximately along line 5-5 of FIG. 2 and looking in the direction of the arrows; and

FIG. 6 is a cross sectional view taken approximately along line 6-6 of FIG. 2 and looking in the direction of the arrows.

Referring now to the drawings and more specifically to FIG. 1, it will be seen that one embodiment of my novel piston knurling device, designated generally by the reference numeral 10, is thereshown. The knurling device 10, as shown, is comprised of an elongate substantially flat base structure 11 having depending flanges 12 integrally formed with the longitudinal side edges of the base structure 11 and defining legs for supporting the base structure in spaced relation with respect to any conventional sup port structure upon which the device is positioned such as a table, bench or the like. The base structure 11 and flanges thereof are preferably cast from a. suitable metal and it is pointed out that the entire knurling device is of a size to be very easily carried by a user.

Means are provided for supporting a piston to be resized and this means includes a substantially flat, vertically extending support post 13 which is also preferably formed of a suitable rigid metallic material such as steel or the like and which has a lower end portion 14 bent at right angles to the upstanding vertical portion, as best seen in FIG. 2. This angular bent lower portion 14 of the post 13 engages the upper surface of the base 11 and is provided with suitable apertures disposed in registering relation With apertures in the base 11 and is secured to the latter by suitable bolt assemblies 15. The upper end portion of the post 15 is also bent at right angles as at 16 and this angularly bent portion 16 has an elongate piston support member 17 integrally formed therewith, as best seen in FIGS. 1, 2 and 6.

The piston support member 17 is spaced above the up per surface of the base 11 to permit support of a piston P thereon, the piston support member 17 extending axially interiorly of the cylindrically shaped skirt S of the piston. It will be noted that when the piston P is mounted on the piston support member 17, the inner surface of the skirt S engages against the upper surface 17a of the piston support member. It will also be noted that this upper surface 17a is of generally arcuate configura tion and corresponds substantially to the inner surface contour of the piston skirt S and the areas thereof located between the conventional wrist pin W of the piston assembly and to which is connected the upper ends of the connecting rod R.

One end of an elongate angularly bent reinforcing element 18 is secured by a bolt 19 to an intermediate portion of the support post 13 while the other end of the reinforcing element 18 underlies and is secured to the pis ton support member 17 by a counter sunk bolt 20, as best seen in FIG. 6. It will be seen that by counter sink ing the bolt 20, the arcuate upper bearing surface 17a of the piston support member may have its arcuate contour substantially retained thereby permitting smooth seating of piston skirts thereagainst which are of predetermined size.

While the upper arcuate surface 17a of the piston sup port member 17 is shaped and contoured to accommodate piston assemblies of conventional size and shape, it is also desirable to permit positive seating of other sized pistons on the piston support member and also to permit accommodation of pistons thereon wherein the inner contour of the skirt may vary. Therefore means are provided for accommodating piston assemblies: which may be; of varying diameters and which may also have skirts with varying inner surface contours, which inner surfaces might not seat in flush engagement with the upper surface 17a of the piston support member.

To this end it will be seen that the piston support mem ber 17 has a plurality of upwardly opening threaded sockets 21 therein, the sockets 21 being arranged in transverse and longitudinal rows, as best seen in FIG. 6. Each socket threadedly receives one of aplurality of threaded positioning and leveling elements 22 which may be ad: justed vertically relative to the sockets 21. It is pointed out that the longitudinal dimension of each threaded socket 21 is slightly greater than the longitudinal dimension of each threaded positioning element 22'whereby permit non-rocking engagement of the inner surface of such a piston regardless generally of the inner contour of the skirt, any selected number of the positioning elements 22 may be adjusted to project upwardly above the upper arcuate surface 17a of the piston support member. Thus it will be seen that the piston support member through the mediary of the positioning and leveling elements 22 can accommodate the pistons having varying inner skirt surface contours and also having diameters of different srze.

Means are also provided for clamping or holding the piston to be knurled against the piston support member 17 to thereby facilitate performance of the knurling operation. This means includes an elongate cam shaft 23 positioned below the base 11, as best seen in FIG. 2, and having ends thereof which project outwardly through openings or apertures 24 formed in the flanges 12. It will he noted that the apertures 24 are elongate in a vertical direction and permit limited vertical adjustment of the cam shaft 23 relative to the base 11.

Each end portion of the cam shaft 23 has an annular bearing element or washer 25 positioned therearound and located exteriorly of and in bearing engagement with the associated flange 12 of the base structure 11. A pair of elongate connecting links 26 each have an apertured lower end through which projects one end portion of the cam shaft 23 to thereby swingably mount each thrust link on the cam shaft 23. The terminal ends of the cam shaft 23 are suitably threaded and a threaded lock element 27 engages one end thereof, the lock element having radially projecting gripping pins 28 secured thereto, as best seen in FIG. 2, to facilitate turning of the lock element. The opposite end of the cam shaft 23 is threadedly engaged by a threaded handle socket 29 to which is secured an elongate actuating handle 30 which is provided with a hand grip knob 31 affixed to the free end thereof. It will therefore be seen that by rocking or swinging the actuating handle 30 the cam shaft 23 may be revolved about its longitudinal axis.

The cam shaft 23, as best seen in FIGS. 2 and 5, has a pair of eccentrically mounted rotary cams 32 keyed thereto for rotation therewith. It will be noted that the cams 32 are symmetrically spaced-apart from the center of the shaft 23 and are disposed in close proximity to the leg flanges 12. One end of an elongate leaf spring 33 is secured to the underside of the base 11 by a suitable bolt assembly 34 and the other end of the leaf spring 33 engages the lower surface of the cam shaft 23 to urge the rotary cams 32 into engaging relation with the under surface of the base 11. Thus it will be seen that revolving movement of the cam shaft 23 by the actuating handle 36'. causes the cam shaft through action of the rotary cams 32 to be moved in an arc towards and away from the base structure 11. v

The upper end of the connecting links 26 are also apertured to permit a piston engaging pin 35 to be inserted therethr'ough as best seen in FIG. 2. This piston engagi'ng pin 35 which is provided with an enlarged head 36 to facilitate handling thereof also extends through the wrist pin W of the piston assembly, as best seen in FIGS. 1 and 2. The piston assembly is clamped against the piston support member by piston engaging pin 35 which is urged downwardly by the connecting links 26 when the carri shaft 23 and cams 32 are revolved by the actuating handle 30. By revolving the cam shaft 23 in the opposite direction, the piston engaging pin 35 may be released from clamped engagement with the piston skirt wrist pin. It is also pointed. out that because of the offset relation of the piston support member 17 with respect to the post 13, the piston P may not only be supported positively and in a level condition for the knurling operation, but this arrangement also obviates the necessity of removing the connecting rod from the piston thereby permitting saving in both time and labor.

The base 11 has a pair of apertures therethrough located substantially along the longitudinal center line plane thereof and each of these apertures receive therethrough the reduced lower end 37a of one of a pair of pivot rod support posts 37, as best seen in FIG. 1. The lower terminal portion of the reduced lower end 370 of each post is threaded as at 37b and is threadedly engaged by a threaded nut 38 having gripping elements 38a projecting radially outwardly therefrom to facilitate turning thereof. Each post 37 may be provided with suitable arcuately shaped spacers 39 which are interposed and clamped between the lower surface of the base structure 11 and the associated nut 38. These spacers 39 may vary in number and may have varying axial thickness dimensions to thereby permit vertical adjustment of the post relative to the base 11. To this end it is pointed out that the spacers maybe positioned between the upper surface of the base structure 11 and the shoulder defined by the reduced lower end portion 37a of each post 37. The removal or addition of these spacers permit ready vertical adjustment of the post 37 and it is pointed out that the adjustment for each post will be substantially the same.

The upper end portion of each post 37 has an aperture 4%) therethrough, the apertures 46' being in substantial alignment with each other and having their axis extending longitudinally of the base 11. Opposite ends of a cylindrically shaped pivot rod 41 projects through the apertures 40 in the posts 37 and this rod is secured against rotation relative to the post by suitable set screws 42. It will be seen that one end portion 41a of the pivot rod 41 is knurled to facilitate handling thereof.

Referring again to FIG. 1 it will be seen that approximately one half the length of the pivot rod 41 has a plurality of longitudinally spaced-apart annular grooves 43 formed thereon so that a plurality of annular longitudinally spaced-apart collars 44 are formed, each collar being defined by an adjacent pair of grooves. It is pointed out that the pivot rod 41 has its longitudinal axis extending substantially normal to the head of the piston P which is to be knurled. This pivot rod 41 serves as a pivot support for an elongate knurling arm 45 which is preferably formed from cast steel or the like.

This knurling arm 45', as best seen in FIG. 1, has a pair of spaced-apart attachment legs or elements 46 integrally formed therewith and extending in substantially right angular relationship thereto. The lower ends of the attachment legs or elements 46 each have a bearing sleeve 47 integrally formed therewith, each sleeve 47 having a bore 48 therethrough through which the pivot rod 41 extends. In the embodiment shown, at least one of the sleeves has a small recess 49 therein which communicates with the associated bore 43 and which has a spring 50 and a ball 51 disposed therein. It is pointed out that the knurling arm 45 is journaled for swinging or pivoting movement on the pivot rod 41 and is also slidable longitudinally of the rod. The spring urged ball 51 will cooperatively engage in any one of the annular grooves 43 on the pivot rod 41 to releasably lock the knurling arm 45 in an adjusted longitudinal position with respect to the pivot rod 41. To release the knurling arm 45 from a locked position longitudinally of the pivot rod 41, it is only necessary to forcibly urge the knurling arm longitudinally of the pivot rod. The spring urged ball will snap into engaging relation through each successive groove 43 as the knurling arm is moved longitudinally of the pivot rod.

An elongated sleeve 52 is integrally formed with the opposite end of the knurling arm 45 and this sleeve adjustably carries the knurling wheel which is used to knurl the exterior surface of the piston skirt. An adjustment block 54, as best seen in FIG. 3, is positioned adjacent the upper end of the bore 53 of the sleeve 52' and is secured in predetermined relation with respect thereto by suitable set screws 55 which extend through threaded recesses in the sleeve 52. This adjustment block 54 has a threaded bore 56 therethrough for threaded envided with an annular groove 57a and a set screw 60 which threadedly engages a threaded recess in the knurl wheel support block 59 extends into the annular groove 57a. Thus the actuator member 57 may revolve relative to the knurl wheel support block 59 and is vertically adjustable relative to the sleeve 52 by its threaded engagement with the threaded adjustment block 54. It will therefore be seen that when the threaded actuator member 57 is revolved, this actuator will also be moved vertically and will also cause vertical shifting movement of the knurl wheel support block 59. support block 59 which is of substantially cylindrical configuration has a bifurcated lower end defined by an axially extending recess 61 formed therein. The knurl wheel 62 is revolvably mounted on the knurl wheel sup port block 5? by means of an axle pin 63 which projects axially from opposite sides of the knurl wheel. It will be seen that the knurl wheel extends into the recess 61 and is vertically movable with the support block 59 during adjustment of the latter.

Means are provided for preventing rotation of the support block 59 during vertical adjustment thereof and to this end the support block 59 is provided with an axially extending keyway 64 formed in the surface thereof and extending substantially throughout the length thereof, as best seen in FIGS. 3 and 4. A threaded set screw or key 65 threadedly engages a threaded aperture in the sleeve 52 and projects into the keyway 64 to thereby prevent revolving movement of the support block 59 during rotation of the actuator member 57.

During operation or use of the piston knurling device 10, the skirt portions of the pistons will be resized so as to increase the effective external diameters thereof. That portion of the piston skirt which is resized by the knurling action constitutes those surface areas or faces located between the ends of the wrist pin W. It will be appreciated that by knurling these surface areas of the pistons, the metal of these surfaces can be swaged outwardly to effect a substantial increase in the diameter of the pistons so that the pistons will more properly fit the cylinders of the internal combustion engine.

The piston assembly P will be positioned upon the piston support member 17 so that the inner surface of the skirt S bears against the upper arcuate surface 17a of the piston support member. As pointed out above, since the piston support member 17 is offset with respect to the post 13, it is unnecessary to remove the connecting rods R from the piston. If the inner surface of the piston skirt does not seat properly and in flush engaging relation against the arcuate surface 17a of the piston support member 17, then the operator may adjust all or some of the positioning elements 22 until the desired bearing surface is presented.

The connecting links are thereafter moved to the vertical position and the piston engaging pin 35 is inserted through the apertured upper ends of these connecting links and through the wrist pin W of the piston assembly. The cams 32 and the cam shaft 23 which will be in the released condition will then be revolved by the actuating handle 30 to cause downward movement of the connecting links and corresponding downward pull on the piston engaging pin. The piston assembly will therefore be urged into seated relation without excessive force against the piston support member 17. The pivot rod 41 will be adjusted to the desired radius by adjustment of the sup- The knurl wheel 6 port posts 37 and the knurling arm 45 will be adjusted longitudinally of the piston rod 41.

It is pointed out that during the resizing or knurling operation, several knurling bands will be formed on the piston skirt and these bands will extend adjacent each other on the faces or surface areas of the piston skirt located between the wrist pin bosses of the piston. Therefore the knurling arm must be shifted longitudinally of the pivot rod 41 after each band is made upon one face of the piston skirt. Each knurled band will be formed on the skirt of the piston by swinging the knurling arm about its pivot axis through an arc of approximately degrees. It is pointed out, however, that the knurling wheel 62 is not in contact with the piston skirt throughout its arc of movement since the radius of the knurling arm is different from the radius of the exterior surface of the piston skirt.

During the knurling operation, the knurling arm is oscillated on the pivot rod 41 to form a plurality of successive bands or if desired overlapping bands on one side of the outer surface of the piston skirt. When the face or surface located at one side of the piston skirt has been knurled, the piston is removed from the piston support member and turned through 180 degrees to present the other face or surface of the piston skirt. S in upwardly facing relation. The knurling bands are successively formed on this face of the piston skirt and the general overall effective diameter defined by the knurled faces will be increased to compensate for the wear occurring along these areas.

As pointed out above, the knurl wheel 62 can be adjusted relative to the sleeve 52 by revolving movement of the actuator member 57. The axis of pivot for the knurling arm 45 which is defined by the pivot rod 41 may also be vertically adjusted by means of the various spacer elements associated with each of the support posts 37. It is pointed out that each face or side of the piston skirt to be treated does not actually extend through an arc of 180 degrees and it is desirable during the knurling operation to decrease the pressure exerted by the knurl wheel as this Wheel approaches the wrist pin bosses of the skirt. Therefore the radius defined by the arcuate movement of the knurling arm 45 is different than the radius of the outer circumferential surface of the piston skirt. The greatest pressure exerted by the knurling wheel will therefore be located substantially midway between the wrist pin bosses of the piston skirt and the pressure will accordingly decrease as the knurling wheel is moved towards opposite sides of this point. It will therefore be seen that each knurling band formed on each face of the piston skirt will in effect taper slightly from the midpoint of the band thus formed.

During this knurling operation the handle structure 58 will be grasped by an operator and the actuator member and knurling arm 45 will be oscillated slowly by the axis defined by the piston rod 41. This deliberate movement minimizes any danger of breakage due to uneven stress being exerted on the piston skirt. The hold down means through the use of symmetrically spaced-apart cams and through the use of an elongate piston engaging pin allows even and substantially equal force to be exerted downwardly on the piston on the skirt so uneven stress is not produced. The entire piston knurling device is of compact, lightweight construction and can be easily carried by an operator from one location to another.

From the foregoing it will be seen that I have provided a compact, portable piston resizing device which is capable of readily knurling the exterior surface of a piston skirt without necessitating the removal of the connecting rod associated with the piston.

It will also be seen that my novel piston knurling device has provision for resizing almost any conventional sized piston used in internal combustion engines and also requires only a minimum of adjustments.

7 Thus it will be seen that my novel piston 'knurling device is not only of simple and inexpensive construction, but one which functions in a more efiicient manner than any heretofore known comparable devices.

It will, of course, be understood that various changes may be made in the form, details, arrangement and 'pro portions of the various parts without departing from the sco e of my invention.

W hat is claimed is:

1. A portable compact piston knurling device for use in knurling the exterior surface of the skirt of a piston, said device comprising a base support means mounted on said base and including a piston support member adapted to support a piston in a predetermined position, said piston support memher, when in supporting relation with a piston, extending axially interiorly of the skirt thereof and engaging the inner -surface of the latter,

means insertable into the conventional wrist pin which connects the associated connecting rod to the piston skirt,

cam means shiftably mounted on said base and being interconnected with said insertable means to cause shifting movement of the latter, said cam means being readily shiftable between released and clamping positions and cooperating with said insertable means to urge the piston against the support member when the cam means is in the clamping position,

an elongate pivot rod mounted on said base and being vertically adjustable relative thereto, said pivot rod being 'longitudina'llly spaced from a piston supported on said support member and in substantial longitudinal alignment therewith,

an elongate knurling arm journaled on said rod for swinging movement relative thereto about the longitudinal axis of said rod, and being adjustable longitudinally of said rod,

and a knurling wheel revolvably mounted adjacent one end of said knurling arm for engagement with the outer surface of the skirt of a piston mounted on said support member.

2. The piston knurlingdevice as defined in claim 1 and cooperating releasable locking means on said pivot rod and said knurling arm releasably locking the latter in a longitudinally adjusted position on said rod.

3. The piston knurling device as defined in claim 1 wherein said piston support member is substantially horizontally oriented and has a substantially arcuate upper surface corresponding generally to the contour of the inner surface-of a piston skirt,

and a plurality of adjustable positioning and leveling elements carried by said support member, each of "said "support elements being variously vertically adjustable relative to said support member between a retracted position below the upper surface of the support member to an extended position projecting above the upper surface of said support member whereby to accommodate pistons thereon of varying diameters and which may have variously contoured inner skirt surfaces.

4. A portable compact piston kuurling device for use in knurling the exterior surface of the skirt of a piston, said device comprising a base,

support means mounted on said base and including a piston support member adapted to support a piston in predetermined position thereon, said piston supporting member, W1 en in supporting relation with a piston, extending axially i'nteri'orly of the skirt thereof and engaging the inner surface of the latter, said support means also being arranged and constructed to support the piston with the connecting rod secured thereto,

an elongate horizontally oriented pivot rod,

an elongate pivot rod support,

means interconnecting said rod With said base and being vertically adjustable relative to the latter whereby the pivot rod is vertically adjustable with respect to the base and is longitudinally spaced from a piston supported on said support member and in substantially longitudinal alignment therewith,

an elongated knurling arm journaled on said rod for swinging movement relative thereto about the longitudinal axis of the rod, and being adjustable longitudinally of said rod,

cooperating releasable locking means on said piston rod and said 'knurling arm releasably locking the latter in the longitudinally adjusted position on said rod,

and a knurling wheel 'revolvably mounted adjacent one end of said knurling arm for engagement with the outer surface of the skirt of the piston mounted on said support member.

5. The piston knurl'ing device as d fined in claim 4 wherein said knurling'wheel is adjustable relative to said knurling arm in a direction substantially normal to the general longitudinal axis of said knurling arm.

6. The device as defined in claim 4 wherein said piston support member has a substantially horizontally oriented convex upper surface corresponding generally to the contour of the inner surface of the piston skirt.

7. A portable compact piston knurling device for use in knurlin'g the exterior surface of the skirt of a piston, said device comprising a base,

an upstanding post mounted on said base,

a horizontally oriented piston support member fixedly mounted to the upper end of said post and offset relative thereto and being adapted to support a piston in predetermined position thereon, said piston support member having a concave upper surface, and When in supporting relation With a piston, extending axially interiorly of the skirt thereof and engaging the inner surface of the latter, whereby a piston may be supported on the support member while the associated connecting rod is secured thereto,

means 'insertable into the conventional Wrist pin which clrgnnects the associated connecting rod to the piston s ir-t,

cam means shiftably mounted on said base and being an elongate knur-ling arm journaled on said rod for swinging movement relative thereto about the longitudinal axis of said rod, and being adjustable longitudinally of said rod,

and a knurling wheel rcvolvably mounted adjacent one end of said knurling arm for engagement with the outer surface of the skirt of a piston mounted on said support member.

8. A portable compact piston knurling device for use in Minding the exterior surface of the skirt of a piston, said device comprising a base,

support means mounted on said base and including a piston support member adapted to support a piston in predetermined position thereon, said piston support member having an arcuate concave upper surface, and when in supporting relation with a piston, extending axially interiorly of the skirt thereof and engaging the inner surface of the latter,

an elongate pivot rod mounted on said base and being wrist pin which connects the associated connecting rod vertically adjustable relative thereto, said pivot rod to the piston skirt,

being longitudinally spaced from a piston supported cam means shifta'oly mounted on said base,

on said support member and in substantially longimeans releasably interconnecting said cam means with tudinal alignment therewith, said insertable pin to cause shifting movement of the an elongate knurling arm having one end thereof dislatter during shifting movement of said cam means,

posed at substantially right angles relative to the general longitudinal axis thereof, said one end having means thereon journaled on said rod to permit pivoting movement of the knurling arm relative thereto about the longitudinal axis of said rod, said knurling said cam means being readily shiftable between released and clamping positions and cooperating with said insertable pin to urge the piston against the support member when the cam means is in the clamping position.

arm being adjustable longitudinally of said rod,

a knurling wheel support member having a knurling wheel revolvably mounted thereon,

and means adjustably mounting said knurling wheel 1 support member at the other end of said knurling arm to permit adjustment of the knurling wheel support member in a direction substantially normal to the general longitudinal axis of said knurling arm, said References Cited by the Examiner UNITED STATES PATENTS 2,494,073 1/1950 Weaver 80-5. knurhng wheel being engageable with the outer sur- 2,635,491 4 /1953 Ben face of a skirt of a piston mounted on said support 2,653,495 9 5 Phillips g 5 1 member and producing a lmurling band when said 2 71 525 9 1955 Phillips 5 1 knurling arm is swung about its axis of pivot. 2 945,405 7 1950 o r 5.1

9. The portable knurling device as defined in claim 8 and an elongate pin insertable through the conventional 25 CHARLES W. LANHAM, Primary Examiner. 

1. A PORTABLE COMPACT PISTON KNURLING DEVICE FOR USE IN KNURLING THE EXTERIOR SURFACE OF THE SKIRT OF A PISTON, SAID DEVICE COMPRISING A BASE SUPPORT MEANS MOUNTED ON SAID BASE AND INCLUDING A PISTON SUPPORT MEMBER ADAPTED TO SUPPORT A PISTON IN A PREDETERMINED POSITION SUPPORT MEMBER, WHEN IN SUPPORTING RELATION WITH A PISTON, EXTENDING AXIALLY INTERIORLY OF THE SKIRT THEREOF AND ENGAGING THE INNER SURFACE OF THE LATTER, MEANS INSERTABLE INTO THE CONVENTIONAL WRIST PIN WHICH CONNECTS THE ASSOCIATED CONNECTING ROD TO THE PISTON SKIRT, CAM MEANS SHIFTABLY MOUNTED ON SAID BASE AND BEING INTERCONNECTED WITH SAID INSERTABLE MEANS TO CAUSE SHIFTING MOVEMENT OF THE LATTER, SAID CAM MEANS BEING READILY SHIFTABLE BETWEEN RELEASED AND CLAMPING POSITIONS AND COOPERATING WITH SAID INSERTABLE MEANS TO URGE THE PISTON AGAINST THE SUPPORT MEMBER WHEN THE CAM MEANS IS IN THE CLAMPING POSITION, AN ELONGATE PIVOT ROD MOUNTED ON SAID BASE AND BEING VERTICALLY ADJUSTABLE RELATIVE THERETO, SAID PIVOT ROD BEING LONGITUDINALLY SPACED FROM A PISTON SUPPORTED ON SAID SUPPORT MEMBER AND IN SUBSTANTIAL LONGITUDINAL ALIGNMENT THEREWITH, AN ELONGATE KNURLING ARM JOURNALED ON SAID ROD FOR SWINGING MOVEMENT RELATIVE THERETO ABOUT THE LONGITUDINAL AXIS OF SAID ROD, AND BEING ADJUSTABLE LONGITUDINALLY OF SAID ROD, AND A KNURLING WHEEL REVOLVABLY MOUNTED ADJACENT ONE END OF SAID KNURLING ARM FOR ENGAGEMENT WITH THE OUTER SURFACE OF THE SKIRT OF A PISTON MOUNTED ON SAID SUPPORT MEMBER. 